1. Field of the Invention
The present invention relates to an apparatus, which tests for shorts and opens in a typical length of Self Limiting Cable (SLC or heat tape).
2. Description of the Prior Art
Self limiting cable includes two parallel conductors which are bonded together in such a way that they are a set distance apart from one another. The pair of wires are surrounded by positive temperature coefficient (PTC) materials, typically a doped polyolefin compound. A typical use of self limiting cable includes thermal protection for pipes or the like in order to maintain such pipes at or above a predetermined temperature regardless of ambient conditions. Applications include building service systems such as sprinkler lines. industrial/commercial processing applications and other critical systems that require temperature control.
Typically. a self limiting cable receives an operating current from a power supply. When the power is applied through the electrical conductors, a resistance between the conductors is developed in the PTC material. The PTC material in turn produces heat which is transferred to the pipes or the like, on which the cable is applied. The cable can be wound spirally about the pipes or layered parallel along the length of the pipe.
During the lifetime of such a self limiting cable. a short or break in the cable may develop which reduces the effectiveness of the cable.